Bistable latching valves are known in the art. For example, U.S. Pat. No. 3,420,492 discloses a bistable latching valve that includes a complex arrangement of two permanent bar magnets which must contact each of two pole pieces of an associated electromagnetic coil. U.S. Pat. No. 4,165,762 discloses a bistable latching valve that requires two solenoids and a so-called snap disc to provide valve on/off positions. U.S. Pat. No. 3,448,960 discloses a latching solenoid valve for controlling flow of corrosive fluid.
U.S. Pat. Nos. 4,533,890; 4,829,947; and 4,779,582 disclose bistable valves in the context of variable operation of valve lifters of an automobile engine. The bistable valves employ magnetized first and second ferromagnetic cores and inner and outer axially magnetized permanent magnets. U.S. Pat. No. 4,938,545 provides a bistable valve in an anti-lock braking system.
An object of the present invention is to provide a pressure relief latching solenoid valve for maintaining fluid pressure in a preset operating range in a fluid circuit with a pressure relief function.
Still another object of the present invention is to provide a fluid circuit, such as a pressurized fuel circuit of a vehicle engine fuel control system, including the pressure relief latching solenoid valve to maintain fluid pressure in a preset operating range and accommodate fluid pressure spikes.